The Young Naturalist's Guide to the
World of the Barrier Beach
Fire Island National Seashore was estab-
lished to preserve the plant-and-animal
communities of one of the few relatively
unspoiled barrier beaches on our Atlantic
coast. Within the boundaries of the National
Seashore, the National Park Service not
only provides for a variety of recreational
activities but protects the natural resource
as an outdoor laboratory for the study of
geology, biology, and ecology. Except for
those living things officially authorized for
harvesting (fish, clams, etc.), and nonliving
things such as shells and other beach
wrack, do not remove anything from the
park without permission.
The Young Naturalist's Guide to the
World of the Barrier Beach
by Bill Perry
drawings by Michael Graham and Missy Lipsett
Division of Publications
National Park Service
^ U.S. Department of the Interior
A Ramble Across the Barrier Island
Birth of a Barrier Beach
How to Be a Beachcomber
Your Beachcombing Kit
After the Storm
Up and Down in the Dune and Swale Zone
What's in a Name?
Mysteries of the Maritime Forest
Wet Your Feet in the Salt Marsh
What Good is a Salt Marsh?
Who's Who in the Zostera Community
The Eelgrass Blight
A Living Fossil: I
Beachcombers All: I
Be a Scavenger: G, I, T
Sunlight and Sand: I
Osmosis: G, /
Profiling a Community: /, G
Comparing Communities: A, I, T
Backyard Ecology: I, G, T, Y
The Eelgrass Microhabitat: I
The Web of Life: G, I, A, T
Maps and Diagrams
The Middle Atlantic Coast
The Origins of Fire Island
Cross-section of Fire Island
The Maritime Forest
Food Web of the Salt Marsh
The Zostera Community
A: For advanced ecology
I: Individual explorations
G: Group explorations — direct
supervision of a teacher or
leader required for beginners
or younger students.
T: Team explorations — 2 to 6
students or a family
Y: Investigations to be carried on
at intervals over a period of at
least one year, or during the
same season in successive
Thanks are due the following persons who helped in
the preparation of this book: Superintendents James W.
Godbolt and Richard W. Marks of Fire Island National
Seashore; Interpretive Specialists Pat Crosland and
Neal R. Bullington; numerous members of the park staff
who provided information and transportation; and
William H. Amos, who reviewed the manuscript and
gave much valuable advice.
William H. Amos: pp. 37, 43, 47, 78, 79; Richard Frear:
pp. iv, 8, 18, 28, 55, 67, 76; Luther C. Goldman: p. 75;
Bill Perry; pp. 4, 5, 9, 12, 15, 21, 32, 34, 40, 41, 46, 47,
48,49, 51, 52, 62, 64; Rex Schmidt: p. 2.
^ z -
A Ramble Across the
Across Great South Bay, the sun appears about to sink
into the low mass of Long Island. You are wading
among patches of eelgrass in the warm, shallow water
off the north shore of Fire Island. Dipnet in hand, you
are seeking whatever kind of animal life you can cap-
ture. The fingersize fish darting about your legs are too
fast. But wouldn't it be a thrill to see a sea horse? Your
chances are slim. This animal is a slow swimmer, but
it is not abundant, and it is well camouflaged in its
eelgrass-jungle habitat. You do manage to catch a few
crabs, dig up one clam with your toes, and scoop a
number of small crustaceans into your fine-mesh net.
Suddenly an enormous horseshoe-crab comes right
toward you, swimming just under the surface and veer-
ing to one side as it is about to bump your legs. Ex-
citedly, you grab it by the long tail spine, drag it to
the beach, and turn it over for a close look. What a
curious creature! As it attempts to right itself with its
tail, you probe between the leaflike "book gills" on its
underside. There you find just what you're looking for:
a large white flatworm, a permanent guest of the horse-
shoe-crab, living on the gills with no evident harm to
the host. Turning the big invertebrate right-side up, you
watch it return to the water. How does it find its way so
easily? You didn't notice any eyes.
Bdelloura (don't pro-
nounce the "B"),
lives on the gills of
The horseshoe-crab, Limulus polyphe-
mus, is actually an arachnid, related to
spiders, ticks, scorpions, and daddy-
long-legs. This non-crab plows the
muddy and sandy bottoms in search of
the burrowing animals upon which it
feeds. In early summer it lays its eggs
in the sand along the shore. Horseshoe-
crabs often carry a bevy of passengers
— permanent guests, not hitchhikers —
including sea lettuce, barnacles, boat
snails, tube worms, limpets, and flat-
worms. Limulus is valuable to science:
blood is drawn from living specimens
(without killing them) and used in medi-
cal diagnosis. Return the horseshoe-crab
unharmed to its habitat.
As the horseshoe-crab swims away, your thoughts
wander back in time — for you have just had a brush
with the world of 200 million years ago, when such
marine monsters as Ichthyosaurus ruled the seas, long
before the great predatory dinosaur, Tyrannosaurus,
appeared on land. This horseshoe-shaped animal with-
out a backbone but with a tanklike outside armor has
lived in Earth's seas virtually unchanged since that era.
No wonder it is called a living fossil!
On the narrow beach you discover that the tide, reced-
ing while you foraged in the bay, has deposited a
wealth of beachcomber's treasure on the sand. Here's
an assortment of flotsam, jetsam, and beach wrack that
could occupy you for hours. Besides a few dead horse-
shoe-crabs and many shed exoskeletons, there are
scallop shells, seaweeds of various shades of brown
and red, assorted driftwood, various items discarded
from boats, and an abundance of plastic bottles and
other ugly reminders that civilization is close by.
More interesting to you right now is a set of hoofprints
running along the high-tide line. A deer has chosen the
easy travel route; passage down the middle of this long,
narrow, roadless island is made difficult by dense
thickets of trees and shrubs. You decide to follow the
deer tracks to see if they'll lead to an island crossing.
The American goosefish, Lophius ameri-
canus, Is so soft-bodied that when it is
stranded on the shore its flat body be-
comes even flatter. It is one of the
angler fishes, and although it preys on a
wide variety of marine animal life it
sometimes lies in wait in the eelgrass
and gulps down fish that approach its
lure — a flap of skin at the tip of the
spine over its great mouth.
A Living Fossil: I
Examine the external anatomy of
Limulus, the horseshoe-crab. You
will notice that it resembles the hoof
of a horse rather than a horseshoe;
probably it was originally named
"horsefoot-crab." Locate the eyes.
How many are there? How does
their position relate to Limulus'
feeding habits? Study the book gills
and swimming appendages. (Later,
find a diagram of the gillbooks of a
spider for comparison. And see if
you can find out how Limulus, which
has no jaws, chews its food.)
Examine the exoskeleton. Can you
find the opening through which the
horseshoe-crab emerged from its
outgrown armor? Except for this slit
around the front margin, your speci-
men will be a complete and accu-
rate representation of the exterior of
A little way along the beach you come to the skeleton
of a goosefish, more than a meter long and almost as
wide. You can well believe the account of a goosefish
that was found to contain the bodies of seven ducks!
Nearly all gaping mouth, with a formidable array of
teeth, it seems a monster indeed. But there is a natural
function for each of its parts, including the great mouth.
Perhaps to a goosefish you would appear as grotesque.
There is still flesh and skin adhering to the bones and
skull of the goosefish, and it emits a putrid odor. But
thinking that the skeleton would make a great conver-
sation piece for your bedroom, you drag it to the upper
beach to leave for the gulls, grackles, and scavenging
invertebrates to clean up. You can return for your
specimen in a few days.
Now the deer tracks turn inland, following a path
through the salt marsh that separates the bay and the
forest. Perhaps this will lead to the ocean beach. Fol-
lowing the trail, you pass first through a ten-meter-wide
forest of reeds that tower high above you with large,
feathery tips waving gracefully in the evening breeze.
Beyond this zone of tall grasses is a band of ankle-high,
odd-looking plants with fleshy stalks and without no-
ticeable leaves or flowers. They look much like the
primitive horsetails — the plants your pioneer forebears
called "scouring rushes" and used for cleaning pots.
The glasswort zone merges eventually into a growth of
head-high bullrushes; a little farther on the bullrushes
mix with high shrubs whose big, pinkish blossoms
remind you of the hibiscus growing back home in the
front yard. Perched on the swaying tip of one of the
tallest of these plants is a male red-winged blackbird,
calling "konk-la-ree! konk-la-ree!"
Your nose wrinkles, and you stop. What is that odor
that reminds you of a disagreeable medicine? It seems
to be coming from some hip-high plants with purplish
flower clusters. You think, "stinkweed" would be a
good name for them.
Phragmites is perhaps the tallest of the
grasses, with the exception of the
bamboos. It grows in both fresh and
brackish water, normally to a height of
3 or more meters; sometimes it towers
to almost 6 meters. It adds picturesque
beauty to the lagoons and estuaries, and
its strong root system helps control ero-
sion on barrier islands and estuaries;
but it encroaches on good wildlife
Indians taught us
to make a bever-
age from sassa-
fras. It is more
cally as a "pio-
neer" tree: in
some areas it is
one of the first
species to come
into a burned or
Glasswort (Salicornia europaea), despite
its resemblance to the horsetails, is ac-
tually a member of the goosefoot family.
Glasswort grows in coastal marshes
over most of the world. Like spinach and
the common garden pest, pigweed,
which are members of the same family,
it is quite edible.
The forest is now only a few steps away. At the border
of forest and marsh you see the plant you've been
warned to watch for: poison Ivy. Tracks and droppings
indicate that the deer lingered here, as if to feed. Could
it be that this plant, so troublesome to humans, actually
provides nourishment for wild animals?
In the diminishing light of early evening, you move into
the forest on a boardwalk trail. You stop, turn down the
legs of your jeans, and apply insect repellent to your
exposed skin; for there is little breeze here to discour-
age the mosquitos. As they fly about your head, you
wonder what possible good there can be in these pesky
creatures. True, they are food for swallows and dragon-
flies. If only they'd leave you out of the food chain!
What an unusual forest this is. There are no tall trees;
you estimate that the biggest in sight is only seven
meters high, although at the level of your eyes the
trunk is almost as big around as your body. Another
tree here has a very familiar look — it's the leaves,
shaped like mittens, some with no thumb, some with
one, some with two. You crush one of the leaves and
hold it to your nose. Sure enough, there's no mistaking
the fragrance of sassafras.
Imagine a fish with a tubelike mouth through which it
sucks its food as through a straw, a pouch in the male's
abdomen in which the young hatch and remain until they
are ready to make it on their own, an armor of interlocking
bony plates instead of scales, and the ability to change
color to blend with its surroundings; an animal that swims
in a rigid upright position with no body movement and just
a faint fanning of the delicate fins, uses its prehensile tail
like a South American monkey's to cling to its slippery
eelgrass perch, and resembles some mythical creature,
half-horse, half-mermaid. Such a creature is the sea horse,
Hippocampus. Though its appearance and behavior
wouldn't make you think so, it is a true fish, having a bony
skeleton and occupying a rung on the evolutionary ladder
about halfway between the primitive lungfishes and the k
highly advanced flounders and mackerel.
Irresistible is the word for this quaint creature. Lacking
the streamlining of most fishes, it seems to defy the laws
of hydrodynamics as it swims stiffly upright. No wonder it
depends upon camouflage instead of speed for protection
from its enemies. It captures its prey, which is chiefly small
crustaceans and crustacean larvae, not so much by pur-
suit as by vigorously sucking in what comes close. It
apparently spends most of its time clinging to underwater
rooted or free-floating plants, where its visibility is low and
the food supply good. Look for it on the bay side of Fire
Island in the eelgrass meadows under a meter or more of
water. Finding one will be largely a matter of luck, for
these animals apparently disappeared from these coastal
waters with the decline of the eelgrass beds in the early
1930s (see p. 86) and are just now on the comeback road
long after the eelgrass returned.
Would sea possum or sea kangaroo be a better name
The forest is alive with birds. You see such fruit-eating
species as robins, townees, catbirds, and thrashers.
You recognize the juneberry trees, having enjoyed their
fruit on many a hike in the countryside. Here there are
also the abundant fruits of black cherry, holly, choke-
berry, and sassafras.
Poison-ivy is scattered through the forest, making you
thankful for the elevated trail. Eventually the winding
boardwalk leads out of the dimness to the top of a high
dune. You can now hear the surf. You are at the border
of the dune-and-swale community. Beyond the fore-
dune a hundred meters away will be the ocean beach
Turning around, you get a tern's-eye view of the forest
you've just left. Looking down on the roof of the densely
shaded community, one might think, "Why, it's almost
like a green carpet I could walk across!" The foliage is
so thick that you can see nothing under the top layer,
and for all one could tell from this viewpoint, it might
be no taller than your knees. What pruning tool has
kept this forest leveled to the height of the dunes that
separate it from the ocean beach?
Rhus toxicodendron, poison-ivy, related
to cashew and pistachio but not to Eng-
lish ivy, grows as a woody shrub or vine.
Its three-parted leaves are borne alter-
nately on the stem. It is common on Fire
Island — so know it, use established
trails, and keep alert.
Everybody's favorite reptile, the box tur-
tle (Terrapene Carolina) ranges as far
north as Maine and Michigan, as far
south as Florida, and west of the Mis-
sissippi as far as central Kansas. It's as
wide-ranging in its diet, which includes
mushrooms, snails, insects, berries, and
earthworms. The female's eyes are nor-
mally brown; if you see a red-eyed box
turtle, it's most likely a male. The plas-
tron (lower shell) of the male is concave.
Glancing down, you see a box turtle on the sand by a
poison-ivy plant. It's a surprising place to see a turtle,
even a land species. You'd have expected it in the
damper low spots of the forest — but here, on the sun-
baked top of the dune?
Before you a broad hollow, extending to your right and
left as far as you can see, separates your dune from the
dune that borders the beach. The vegetation in this
zone is neither as dense nor as tall as that in the forest
you've just left. Junipers, hollies, and pitch pines,
pruned to the contours of the dune, cover the top of the
dune; but as you go down the face these give way to a
variety of plants growing in low clumps separated by
bare sand. One shrub, with dense clusters of small,
white flowers like wild roses, catches your eye; it's the
same plant from which, on a September weekend, you
gathered beach plums for home-made jelly. It has two
growth forms here — sprawling on the ground and
standing upright. A few meters away a cottontail is
nibbling on one of these shrubs.
Suddenly a mallard duck zooms in over your head and
makes a landing in the midst of the brushy vegetation.
This is a strange habitat for waterfowl, you think. On
the other hand, there would certainly be good hiding
places for a nest under the thick clumps of shrubs and
sprawling pitch pines.
Continuing on the boardwalk across the swale, you
reach the top of the dune bordering the beach —
the primary dune, or foredune. It slopes steeply to the
high-water mark, and here the woody plants have given
way almost entirely to clumps of beach grass.
The breeze is stronger than it was on the bay side of
the island, and you can feel salt spray on your face. The
cries of wheeling gulls and terns pierce the rhythmic
roar of the surf. Two herring gulls are foraging for food
at the line of wave upwash. What is the sea bringing to
them? The graceful, hovering terns drop at intervals to
the surface beyond the breakers; whatever they're fish-
ing for must be small, for you can't see anything in
You, too, are lured to the beach. Removing your shoes
and again rolling up your jeans, you run down the
broad slope toward the water. Suddenly three small,
sand-colored birds you hadn't noticed fly up in front of
you and settle again on the sand about 30 meters down
the beach. As the waves wash up the beach, the little
birds dash back and forth almost as if playing tag with
the water; but as they follow each receding wave they
jab their bills repeatedly into the sand. You walk toward
them, hoping to get close enough to see what they're
picking up. Again they fly up, white wing-bars flashing,
to land a safe distance away and resume their game
of catch-me-if-you-can with the waves.
For a while you try the same sport; you soon discover
that it's impossible to predict how far each wave will
run up the beach. Standing still, you enjoy the sensa-
tion of having the receding waves wash the sand out
from under your feet. Would you sink out of sight if you
stayed long enough? How quickly your footprints dis-
appear when you walk away! This must be a difficult
environment for animals. You wonder how the birds can
expect to find living things in these shifting sands.
With such questions in mind, you decide to come back
tomorrow with a digging tool. But now the sky is dark-
ening rapidly, for the sun is well below the horizon.
Buttoning your windbreaker, you gather up shoes and
equipment and walk along the beach toward camp.
Birth of a Barrier Beach
To retrace the origin and growth of Fire Island, we must
go back many thousands of years — to the Pleistocene,
long before the birth of the island. During that epoch
great ice sheets moved a number of times far down into
the continents of the Northern Hemisphere. The last of
these advances almost reached the point where Fire
Island is now located. Great masses of rock material
borne in and on that glacier were carried by glacial
streams far beyond its terminus. The rocks, silt, and
sand were deposited by the streams in fan-shaped
formations. A long row of these "outwash fans" — so
close together that they overlapped — was the founda-
tion for most of Long Island.
About 11,000 years ago, the ice sheet began to melt
rapidly. The mainland at that time extended south
beyond today's beaches; Long Island was then only a
low ridge on the outwash plain, and Long Island Sound
a river valley in the plain. So much of Earth's water was
tied up in the ice sheets that the ocean was a hundred
or so meters lower than it is today. But as the ice
melted, sea levels rose. By about 4,000 years ago they
reached the level of today. The ridge became Long
Island as the sea moved into the valley and separated
it from the mainland. The south shore of Long Island
.„ between Montauk Point and Southampton was at this
Limit of glacial advance
time about 2 kilometers beyond its present location.
Thus the stage was set for the long process that cul-
minated in today's Fire Island. (Keep in mind that the
process is still occurring, that Fire Island is a dynamic,
not a static, geologic feature.)
How did the Long Island shoreline move back to this
point, and how did Fire Island develop where the main-
land formerly existed? The name of the game, you
might say, is "Erosion and Deposition." The tools used
to play the game were wind, waves, and currents.
The Middle Atlantic Coast
Long Island, its barrier beaches, and
Cape Cod all owe their existence to the
Pleistocene glaciers; but the barrier
beaches to the south consist largely of
sand carried down by rivers from
eroding mountain ranges.
Barrier islands, as we call these wave-and-current-
built, linear islands, are developed only where the land
slopes gently beneath the sea. Here the glacial outwash
plain extended well out beyond the shoreline as the sea
rose and advanced landward. Under such conditions,
winddriven ocean waves pick up sand from the shallow
bottom and build it into an underwater ridge, or sand
bar. With the help of longshore drift (see p. 16), the bar
is built up above sea level, and we have what we some-
times call a barrier beach, separated from the mainland
by a shallow bay, or lagoon. (Long Island is Fire Is-
land's "mainland," and Great South Bay is its lagoon.)
But Fire Island is not a typical barrier island, and its
story doesn't quite conform to the pattern. The island
began its development perhaps 3,000 years ago as the
sea carved away at the headlands between Montauk
and Southampton. Sand carried by the longshore cur-
rents (see diagram) built up a spit that grew westward
at an average rate of some 25 meters per year. Wind
and waves built the spit higher and wider, forming the
dunes and the "sand apron" behind them.
In those 30 or so centuries, the sand spit has grown to
a total length of about 80 kilometers; but its average
width has never exceeded 300 meters. Sometime in
direction of waves
The Origins of Fire Island
Long Island is a part of an outwash
plain that remains above sea level,
which today is about 100 meters higher
than it was during the Pleistocene. Long
Island Sound is an inundated part of
that outwash plain. Fire Island and other
barrier beaches are made up of sand
eroded by the waves from the post-
glacial shores and carried southwest-
ward by longshore drift.
Southwestward migration of the spit that
is now Fire Island.
recent centuries storms breached the spit at two points,
and the section farthest west is now Fire Island, which
is separated from the middle section by Moriches Inlet.
It is still a child of its "mainland," getting its growth
from sand eroded from the Montauk-Southampton
shore. Fire Island today is a little more than 50 kilo-
As the diagram shows, Fire Island is not only growing
longer year by year; it is moving toward the mainland.
This migration occurs because wind, waves, and cur-
rents are removing more sand from the ocean side of
the island than is being deposited there. Much of the
sand is piled up on the beach by wind, tide, and waves
and is blown landward, extending the sand apron and
the marshland and encroaching on Great South Bay.
Some sand is carried into the lagoon through Moriches
and Fire Island inlets, and this helps to extend the
marshland, build islands, and fill in the lagoon. It is
entirely possible that this landward migration will con-
tinue until Fire Island becomes a part of Long Island.
Perhaps ocean waves will then build up new sand bars
that with the help of the wind will develop into new
barrier islands occupying almost the same locations as
do the present chain of islands. But none of these
developments will come to pass in your lifetime.
How to Be a Beachcomber
The sprightly shore bird you saw playing tag with the
waves on your early evening walk from the bay is the
beachcombing champion of Fire Island, the sanderling.
It is well named, because it likes sand beaches, and
because its coloration blends well with the beach sand.
But it could just as aptly have been named "wander-
ling," for it is a champion globetrotter, too, known to
lands around the Earth from the Arctic almost to the
Antarctic. A sanderling that summers on the northern
shore of Greenland may fly in winter to the south coast
of Australia. And it's not even as large as a robin.
You can see these birds from fall through spring and
sometimes in summer; and you can learn from them
some valuable lessons in beachcombing. Observe care-
fully as they forage for food. Watch a sanderling dash
on slender legs up and down the beach slope with the
advancing and retreating waves at its heels. When a
wave seems about to overtake it, the little shore bird
may just flutter above the beach for a moment, then
alight and follow the receding wave back downslope.
This game of tag is actually a most efficient way of get-
ting food, for small organisms living in the sand are
closest to the surface when it is being washed by in-
coming and receding waves; and the waves deposit
other organisms carried in from the offshore waters.
Notice that as the sanderling's twinkling legs carry it
over the wet surface, it makes repeated downward
thrusts of its awl-like bill. If you were able to examine
this operation closely, you'd find that, probing the sand
with slightly opened bill, it is extracting tiny animals —
shrimp and other crustaceans, marine worms, mollusks,
and invertebrate larvae.
So here's your first lesson: look along the water's edge
for small animals. But they are not usually abundant in
this severe environment, and you'll need a magnifying
glass — 10-power or more. And unless you're as nimble
as a sanderling, plan on getting wet feet.
Your Beachcombing Kit
At little expense, you can make up a kit of handy beach-
study aids that can be carried in a plastic shopping bag.
Some useful items are 10-power magnifying glass, ther-
mometer, binoculars, wide-mouth glass jar or clear plastic
container, magnet, sieve or sifting box, trowel, metric
ruler, and collecting bag. You may want field guides for
bird or shell identification. A camera (with close-up lens)
is a good record-keeping tool and a means of "collecting"
specimens of living animals that you're not allowed to
remove from the beach. And don't forget notebook and
These chains of papery, hollow discs
found on ocean and tidewater beaches
are the empty egg capsules of large,
carnivorous marine snails called whelks.
As many as 200 eggs are enclosed in
There are certain clues that will help you find life in the
sand. Most of the small holes you see are "percolation
holes" made by air escaping from the sand; a few may
be the entrances of burrows. Footprints indicate where
birds have been foraging. Look for smaller creatures
living in the spaces between sand grains; for this you'll
need a strong lens or even a microscope. Digging and
sifting will bring forth such animals as razor clams, soft-
shelled clams, and the burrowing amphipod, Haustorius,
a relative of the beach hoppers that is more closely tied
to the sea.
Donax, the active little coquina, or bean clam, normally
found on southern beaches, arrives at Fire Island as a
larva carried in the Gulf Stream. It moves up- and
downslope with the tides. When a wave reaches the
point where it lies buried, Donax leaps out of the
sand and rides up on the wash. When the wash recedes,
it quickly anchors itself, upends, and digs in.
Actually, most of the life of the intertidal zone consists
of fish and plankton that come in with the tide. Few
animals and fewer plants have adapted to existence in
this unstable, abrasive, and difficult habitat. When the
tide is out, the sand is hard-packed. When the surf is
washing it, the sand is subjected to violent motion. As
Beachcombers All: I
Compare the feeding habits of ani-
mal visitors to the ocean beach.
Examine such questions as:
Do you ever see terns feeding on
Do such shore birds as sanderlings
and sandpipers use the same tech-
niques for getting food as do the
Which birds depend on the waves
to bring fresh food?
you will discover if you visit the beach the day before
and the day after a storm, it can change dramatically
overnight. Where you saw a 100-meter-wide beach,
there may remain only a 50-meter strip between the
foredune and the sea. A storm may remove the entire
population of an animal such as the mole crab, which
might not recover for years. Even after a long spell of
moderate weather, you will do well to find a half-dozen
species of animals below the surface of the sand.
But with the lack of variety of life forms in this environ-
ment, those species that have adapted to its stresses
occasionally reach enormous numbers. The sea brings
an unlimited supply of food to this zone, and popula-
tions can build up rapidly.
What songbirds do you find visiting
the beach, and what are they
Can you explain why in the intertidal zone of Great
South Bay you'll find a much greater variety of forms
than you will find on this exposed ocean beach?
What information can you get from
tracking mammals on the beach?
Which visitors are scavengers?
Each kind of animal in the intertidal beach occupies a
zone that is strictly limited by the physical conditions.
For example, the mole crab's feeding techniques re-
quire that it remain in a narrow zone that moves back
and forth with the tide; the crab does not ascend as far
as the upper intertidal zone.
Anyone interested in seashore life should become ac-
quainted with the group of small crustaceans called am-
phipods. There are more than a thousand species, and all
are flattened sideways, which makes them easy to dis-
tinguish from other crustaceans. They range in size from
near-microscopic to about 30 millimeters long. Because of
their abundance and because many animals eat them,
they are important ecologically.
The sand hoppers of the ocean beach are gilled air
breathers. Their three hind pairs of abdominal feet are
adapted for jumping, and the three front pairs for swim-
ming. As though these animals were on the evolutionary
road from a marine habitat to a dry-land existence, the
jumping feet are much the larger. But the usual route from
sea to land is not direct; rather, it is via estuaries and fresh
water. No crustaceans, moreover, have entirely adapted
to dry-land existence — not even the sowbugs you find
under boards in your back yard.
Apparently the small amount of moisture under the drift-
wood and seaweed is enough for the upper-beach am-
phipods. They feed upon the seaweed and upon dead
animals, and in turn are fed upon by a host of predators:
sandpipers, sanderlings, insects, centipedes, and many
At the shore on the bay side of the island, you'll find other
amphipods, as well as the distantly related isopods, which
are flattened from top to bottom.
swim, walk, or
jump, and would
except for their
At low tide, stand barefoot on the part of the beach being
washed by the waves. As each wave recedes, watch the
sand where the water is flowing down the slope of the
beach. If you're sharp-eyed, you may see a pair of tiny,
featherlike objects project from the sand only to disap-
pear when an incoming wave washes up the slope. Dig
quickly into the sand where you saw the "feathers;" with
luck you'll find a small, smooth, egg-shaped animal. This
is the mole crab, which buries itself head up just beneath
the surface of the sand in the lower part of the intertidal
zone. When the waves are receding — not advancing — it
extends its plumelike antennae to strain food particles
from the water. As the tide ebbs and flows the mole crabs,
which can swim, move with it so as to remain in the feed-
ing zone. The females, as much as 40 millimeters long,
may be too big for the sanderling to swallow; but the much
smaller males are probably taken by this bird.
The best tool for turning up large scoops of the sand is a
small spade, like the folding entrenching tool sold in sur-
plus stores. You'll have to work fast, for the mole crab is
an amazingly adept burrower. One of its predators, the
swimming crab, has developed an efficient means of cap-
ture: it shoves its large claw downward into a bed of sand
crabs. If it manages to grab one, it begins running in a
circle, all the time holding onto its victim. The twisting
motion enables it to pull the sand crab out of the tightly
packed sand much as you'd pull the cork out of a bottle
If you get one, put your specimen into a wide jar filled with
sea water and with about 50 millimeters depth of sand in
the bottom. Then drop the mole crab into the jar. It will
burrow into the sand so quickly you'll miss it if you blink!
This ability, an adaptation to life at the edge of the ocean,
is due partly to its streamlined shape. Examine the crab
with a magnifying glass; you'll see the several pairs of
short, stout legs that enable it to dig in backwards. Study
the branched breathing antennae, the feathery feeding
antennae, and the eyes on very long movable stalks.
To learn more about this remarkable crustacean's adapta-
tions, life history, and behavior, read The Life of the
— «. -■- *
The razor clam, so named because it is shaped like an
old-fashioned straight razor, shares the mole crab's
reputation as a fast burrower. But it lives in quieter sandy
intertidal areas, where there is not the active surf so nec-
essary to the mole crab's existence. Like the mole crab it
cannot burrow in dry sand; but in the watery lower inter-
tidal habitat it is a wizard at the disappearing act.
t •••••• ■<
W?fr. it- ■'■
The razor clam, which may reach 25 centimeters in length,
occupies a vertical hole without any sand piled around the
opening. It feeds when its burrow is covered with water,
with part of its shell sticking above the surface of the sand.
When the tide is out, you may be able to dig up a razor
clam — but you'll have to move fast, for it has a muscular
"foot" that enables it to descend quickly beyond your
reach. Try to get it with the first fast spadeful of sand; if
you miss, you might as well move on to another clam hole.
. - i'.rt
Like the sanderling, you shouldn't limit your beach-
combing to the intertidal zone. You'll find the pickings
less slim and the foraging easier on the upper beach.
This is the zone between normal high-tide mark and the
"toe" of the primary dune (see p. 46). It's good for sun-
bathing and play, and also has lots of animal visitors.
But when you consider the prevailing conditions —
sands being shifted constantly in the wind and removed
wholesale by storm waves; so much salt that the sur-
face of the sand is often crusty with it; a lack of organic
matter to provide food for burrowing animals; and ex-
tremely dry conditions near the surface — you can under-
stand why few animals are permanent residents. If
you've walked barefoot across the upper beach on a
midsummer day, you can also understand why animal
visitors might be scarce at midday.
On the upper beach as in the intertidal zone, the sand-
erling's favored food is crustaceans. These include
sand hoppers ("beach fleas"), abundant animals hardly
more than a centimeter long that hide in vertical bur-
rows in damp sand or live under the windrows of drift-
wood, fish remains, shells, dead seaweed, and other
debris at high-tide mark. Kick over some of this "beach
wrack" and watch the little crustaceans jump like the
fleas for which they have been named. There are also
Be a Scavenger: G, I, T
Make a bulletin-board display, or a
mobile sculpture, of things found on
the beach. Try to have a specimen
representing each of the major ani-
mal groups of the marine ecosys-
tem — a fish skull, a horseshoe-crab
shell, bird feathers, and a mollusc
shell — as well as driftwood, dried
seaweed, and other plant material.
predatory and scavenging beetles, and flies and (on
dead fish or birds) fly maggots. Together with gulls and
visiting scavengers from the island's interior, these are
nature's garbage collectors for the beach community,
keeping dead plants and animal carcasses from piling
up. (The gulls are also efficient removers of picnic
scraps, and prey upon horseshoe-crabs and other live
animals cast up by the waves.) Carnivorous centipedes
and herbivorous millipedes are also found here.
You can learn much about the beach community and
the life of the sea by combing this zone for skeletons,
shells, egg cases, and other animal remains. At high-
tide mark and in the storm-wave zone look for the
shells or dead bodies of horseshoe-crabs, which live in
the ocean as well as the bay; for those necklace-like
chains of whelk egg cases that mystify many a visitor to
the beach; and for fish skeletons, which are more varied
than you'd guess. Some of your discoveries will have a
tragic note; too often, today, the beachcomber finds a
sea bird, its feathers soaked with heavy, black oil, cast
dead or dying upon the shore.
If you keep a record of where you discover each living
thing-above high-tide mark; in the intertidal zone; in
the sand being washed by the waves; above or below
Want to enjoy wildlife-watching the year
around? Learn to identify gulls, terns,
and shorebirds, the most conspicuous
animals of the seashore. Observe their
feeding behavior, plumage patterns,
manner of flight, and calls. The sand-
pipers, including the sanderling, are a
big family that will require a lot of prac-
tice on your part. A bird guide and
binoculars are essential. The bird in the
picture is a herring gull.
the surface-you'll gradually piece together an ecologi-
cal jigsaw puzzle: the pattern of life communities and
the habitat requirements of different species. You'll
observe that some animals, such as the sanderling, are
not restricted to a single community or habitat. Others,
such as the mole crab, because of their food require-
ments and special adaptations to the environment, are
never found beyond their special narrow zone, except
by accident. Each of the life forms of the ocean beach
has developed structural adaptations and behavior
patterns that enable it to cope with physical hazards,
find food, and protect itself from its enemies. It is this
great variety of life styles that makes even this austere
environment — almost a desert when compared with the
rich bay community — an interesting place to explore.
As your observations and examinations accumulate,
you will begin to see emerging a pattern of seashore
life — a structure much like that of a human community,
in which each organism has a function, or "niche" in
After the Storm
The most productive time for beach exploration is the day
after a storm; the bigger the blow the better the beach-
combing. But stay well above the dangerous surf that per-
sists after the wind abates. Probe the windrows of jetsam,
driftwood, and dead plants for animals cast up by the
storm waves. You will find the valves of many molluscs,
including such forms as the sea butterfly, knobbed whelk,
shark' s-eye, transverse ark, jingle shell, and false angel
wing; dead sand sharks and sea robins; and perhaps liv-
ing specimens of surf clam, starfish, blue mussel, large
hermit-crab, Tubularia and other hydroids, bryozoans,
Up and Down in the Dune
and Swale Zone
The zone behind the beach is in some ways the most
severe environment of Fire Island. It is very close to a
desert in its physical characteristics; and the plants and
animals that are able to thrive here have adaptations
similar to those of desert species. Every living thing in
the dune-and-swale community is modified in its habits,
structure, and life history to cope with heat and dry-
ness. And any part of this zone is subjected to heavy
doses of salt spray, in varying degrees depending on
whether it is on a windward (ocean) or leeward slope
and on how far it is from the ocean. Thus, only plants
tolerant of salt can succeed here.
It is true that the dune-and-swale zone gets as much
rain as the other island communities. But the porous
nature of the sand allows rainfall to percolate rapidly
down beyond the reach of ordinary plant root systems.
This means that plants either must produce a root sys-
tem that reaches to unusual depths or must have spe-
cial adaptations to conserve what moisture they can
capture during the rains. Animals either must go out-
side the zone for water or must have the capacity to
survive on moisture obtained from food.
Let's explore this community by starting at the "toe" of
the foredune — the upper edge of the beach. Here, even
Beach grass, Ammophila breviligulata, a
most important plant ecologically, is
found on the coast from Newfoundland
southward and on sandy shores of the
Great Lakes. It spreads mainly by send-
ing up shoots from the joints of creeping
rhizomes, or horizontal underground
on the beach itself, you may see an intriguing plant
with an intriguing name, "dusty miller." You'll know it
because it looks as though it had been dusted with a
white powder — much as an oldtime flour miller might
be. Its floury appearance is due to a dense matting of
white fibers that insulates the plant against light and
heat and probably provides some barrier to evaporation
of moisture. Obviously, a plant growing in such a loca-
tion must be very tolerant of salt spray.
Now let's go up the face of the foredune — via a board-
walk or other designated crossing. Here the dominant
plant is beachgrass (Ammophila breviligulata). This
plant is so effective in stabilizing the dune with its
spreading roots that it is often planted in dune-restora-
tion work where human traffic has trampled the vegeta-
tion or a heavy storm has caused damage. The preva-
lence of beachgrass on the ocean side of the foredune
suggests that, like dusty miller, it has great tolerance
for salt spray. Patches of beach-plum and bayberry
shrubs occur among the beachgrass.
At the top of the dune another shrub, bearberry, ap-
pears. As you go downslope, the shrubs become domi-
nant and beachgrass diminishes. In the more open
areas where there is much bare sand, woolly beach-
In hollows (including the swale itself,
which is a large hollow), the sloping
sides reflect sunlight and radiate heat
toward the center, raising temperatures
to levels as high as 50° C.
Artemisia Stelleriana is the scientific
name of beach wormwood, popularly
known as "dusty miller" — a name ap-
plied to at least four other plants. Arte-
misia is most conspicuous on the wind-
ward side of the foredune, and a few
plants even grow on the upper beach.
It is too scattered to be of importance
as a dune-holding plant. Like saltspray
rose, it is an Asian plant that escaped
from American gardens and spread
along our Atlantic coast.
heather and seaside goldenrod are common. Look
closely at the beachheather; notice its heavy, scalelike
leaves — an adaptation against water loss and heat.
The dip between the primary dune and the secondary
dune is called a swale. You'll find changes in the veg-
etation here that reflect the changed conditions. Does
it seem hotter here than it was at the top of the dune?
Of course the swale is shielded from cooling sea
breezes. But as shown in the diagram, there is a further
reason: when the sun is high the slopes of a swale or
hollow in the dunes act much like a lens or reflector to
concentrate the sun's rays. So plants growing in the
bottom of the swale have to contend with greater heat.
On the other hand, being closer to the water table (see
diagram), they may have less difficulty reaching mois-
ture with their root systems. Animals, being mobile,
cope by remaining in burrows or escaping to other
parts of the zone during the hottest part of the day.
And what animals can you expect to find in this com-
munity? You found that the beach and intertidal zones,
unlike most natural communities, were populated pri-
marily by animal forms. The green plants that are the
base of the food web in these communities are the
algae and plankton plants of the sea. The living animals
What's in a Name?
Why do we use Latin names such as Ammophila brevili-
gulata or Artemisia Stelleriana when it's so much simpler
to call the former "beachgrass" or to use the more inter-
esting name of "dusty miller" for the latter? For one thing,
most of the 1,000,000-plus known species of animals and
375,000 species of plants have no names other than the
Latin binomials ("two names") given to them by the scien-
tists who classified them. Secondly, "beachgrass," for
example, would be used only by English-speaking people;
its Latin name is universal. Moreover, there are other
species of grasses that can quite properly be called
beachgrass — and some persons might refer to any grassy
plant growing on the beach as "beachgrass." And to con-
fuse matters further, there are other acceptable English
names for beachgrass: sand-reed, psamma, dunegrass,
and marram. One name might be used in one locality,
another in the next county. Ammophila breviligulata, on
the other hand, refers to one species, or kind, of plant,
wherever it grows. Another "beachgrass," Ammophila
arenarja, belongs to the same genus (plural: genera), or
closely related group of species, Ammophila. Their differ-
ent specific names, breviligulata and arenaria, reflect the
fact that the seeds of each will reproduce only that kind of
plant. Ammophila breviligulata seeds will not produce
Ammophila arenaria plants, and the pollen of one will not
fertilize the ovary of the other.
If you were to mention (t beachgrass" to a European scien-
tist who did not speak your language he would not know
what plant you meant. But Ammophila Is a genus with
species on both sides of the Atlantic, and the Latin name
of each would not only be spelled the same everywhere,
but would have basically the same pronunciation.
The generic name is always capitalized. The specific
name is not — except when it applies to a plant named for
a person. (Artemisia Stelleriana was named in honor of the
great 18th-century German explorer-naturalist Georg
* * ^ *
^ * **
* ** *
of beach and intertidal zones depend mostly on food
brought in by the waves. But here in the dune-and-
swale the situation is normal — a variety of rooted green
plants is the food base. In crossing this zone, you will
see as many as two dozen plant species.
Except for birds that visit the dunes to feed on berries,
there are few vertebrates here. The white-tailed deer,
which roams over all the island, is a visitor to the
is not found on the
windward face of
the primary dune;
but in the swale it
is more prominent
/n the picture, the tracks of a fox merge
with those of shore birds. Is there a
swale. This leaves only the cottontail and meadow vole,
and sometimes the red fox, to represent the mammals
as regular residents. You may see cottontails nibbling
on the beach plums and other shrubby plants on cooler
days or when the sun is low. But the voles come out of
their burrows only at night.
If you visit the dune-and-swale community in early
morning, before the wind has had a chance to obscure
all the signs of activity, you will find the surface criss-
crossed with tracks of many kinds of animals. It is often
possible to identify the maker of a particular track; and
you may be able to recreate an encounter between prey
and predator by studying the signs in the sand. One
peculiar, corkscrewlike trail belongs to one of Fire
Island's two common snakes, the eastern hognose. If you
happen to meet this reptile, you may be startled by its
defensive maneuvers. Upon your approach, it will
spread its neck as if in imitation of the cobra, open its
mouth wide, and hiss menacingly. It may strike at you,
too, but its strike will fall short. It is only bluffing; even
if it did bite it would do you no harm. Stand your
ground and see what happens. If its threatening actions
don't drive you off, it may suddenly roll onto its back as
if dead. If this happens, turn the snake right-side-up; it
will immediately flop again onto its back! While these
antics of the hognose have made it some friends among
nature lovers, it has unfortunately been much perse-
cuted by man. Many insist that it is poisonous and
vicious, and upon encountering the "puff adder" their
first reaction is to dispatch it with a rock or stick. At
the National Seashore, however, it is protected by law.
The hognose snake is highly specialized in its diet; as
in other parts of its range, it lives primarily on toads
here. The only toad on Fire Island — the only amphibian,
in fact — is Fowler's toad. Like the hognose snake, this
toad has become adapted to life on the dunes; it is
inactive during the hottest hours of the day, keeping
cool and moist by burying itself in the sand. (In cooler
habitats that provide shade, this would not be true.) It
feeds on a variety of insects, which it captures with its
The invertebrates, or animals without backbones,
include 97 percent of all the world's known animal spe-
cies, but they are represented here by relatively few
classes. No earthworms or other animals with moist
skins can tolerate the hot, dry sands. Insects are the
dominant group of invertebrates here as in other land
The hognose snake, Heterodon platy-
rhinos, inhabits sandy areas throughout
eastern United States except in Maine.
On Fire Island its chief prey is Fowler's
toad, Bufo woodhousei fowleri. Unlike
frogs, toads generally have dry, warty
skins and hop rather than leap. They are
not as much bound to water as most
frogs, but return to water to breed and
occasionally to soak. Fowler's toad is a
late breeder, laying eggs until mid-
Sunlight and Sand: I
During early afternoon make a se-
ries of temperature readings at a
spot on the foredune or secondary
dune that is fully exposed to sun-
light. Read the temperature one
meter above the sand (be careful to
shade your thermometer from the
sun to be sure of getting the air
temperature); 5 centimeters above
the sand; just under the surface of
the sand; and 5 and 15 centimeters
under the surface. How does this
relate to the egg-laying behavior of
the bembecid, or digger wasp, and
to the daily schedule of activity of
the Fowler's toad?
environments. Special structural adaptations or be-
havior patterns enable many of them to survive in desert-
like conditions. Some beetles move up and down the
plant stems, varying their distance from the hot sand as
its temperature changes. Some insects burrow under-
neath by day and come out at night. Some are light-
colored, like many desert species, and absorb the heat
of the sun less readily than do darker animals.
Successfully coping with the heat and dryness of the
dune environment are the abundant ants of various
kinds. Dune ants are burrowers; some have special
sand-carrying apparatuses on their heads that make it
easier for them to dig deep into the sand to a level
where it is cool and humid. The ants avoid activity on
the surface during the hot part of the day.
Mammals are less conspicuous than birds on Fire
Island, but if you keep your eyes sharp you're sure to
see the cottontail. Take a walk at daybreak; the red
foxes are particularly active then. Watch for a fox den in
the side of a dune. In spring you may see several cubs
playing about the entrance. Without these predators,
the plant-eating cottontails might become so abundant
as to cause severe damage to the environment.
A community in nature can be defined as the living part of
an ecosystem — that is, the association of plants and ani-
mals living in a particular physical habitat. An example:
all the organisms in a pond, including, at particular times
of the day or during particular seasons, those visiting it
from other habitats. Plants growing around the edge
because of conditions of moisture deriving from the pond
might be considered part of the pond community; or, if a
large area adjacent to the pond is vegetated by cattails
and other rooted emergent plants, it would be called a
marsh community. The two may overlap, and many animal
forms might belong to both. (Such a transition zone is
called an ecotone.) Study of the living things in any habitat
will soon convince you that all are interrelated and inter-
dependent, through such factors as competition, (for living
space, food, etc.), predation, parasitism, commensalism,
and habitat modification (as in the building of beaver
A community need not be as large as a forest or a lake.
It can be as small as a decaying log or stump with its
myriad of organisms including mosses, fungi, bacteria,
insect larvae, burrowing beetles, ants, etc. The log itself
can be referred to as a "microhabitat." If you have a
"balanced" aquarium — one that needs addition of neither
food nor oxygen to keep it functioning — this is a micro-
habitat with a living community. (What is the source of
energy for the balanced-aquarium community?)
A natural community, when you think about it, is compara-
ble to a human community, in which an association of
living things (man, pets, livestock, trees and other plants,
pests, and wild animals) are living together in a physical
habitat altered or largely created by man. Just think of the
many ways in which all the plant and animal inhabitants of
the human community are interdependent and interre-
lated, and it will be easy to draw parallels with the natural
Distance from ocean
Cross-section of Fire Island
dune and swale
beach plum beachgrass
220 Distance from ocean
Great South Bay
The sun provides the energy by which green plants con-
vert raw materials (water, carbon dioxide, and minerals)
into living matter. Plant eaters in turn convert the carbo-
hydrates and proteins of vegetation into animal tissue.
Predators, relying on animals tor their food, are just as
dependent on the green plants as are animals that eat
green plants directly. In the dune-and-swale community,
we can illustrate this flow of energy with a simple food-
cottontail ► red fox
Each arrow indicates the direction of the flow of energy
from an organism to the organism that eats it. The food
. , 8S8' 'S ;
•V 1 !
chain ends with an animal that is not normally preyed
upon. (There are no predators on the red foxes of Fire
Island.) At each level of the food chain, about 90 percent
of the energy is lost. It requires at least 10 kilos of beach-
plum food to produce one kilo of cottontail, and that kilo
of cottontail will produce only 1/10 kilo of red fox. Some-
times the red fox eats the fruit of the beach plum, and then
we have a shorter food chain and a more direct process
for converting plant food into fox flesh:
beach plum ► red fox
A food web, made up of many interlinking food chains,
is shown in the chapter on the salt-marsh community.
I," w*§kW> i
• _> V.
szP : j
^ : : x -A,
the Maritime Forest
How did this strange woodland with the peculiarly
cropped appearance come about? It looks as though a
giant with a hedge clipper had tried to level it off even
with the dune crest. And from your viewpoint on the top
of the secondary dune the roof of the forest seems as
dense as a hedge. The trees appear to be filling a great
hollow, but this is somewhat deceptive. As you walk
through the forest toward the bay, you will be gradually
descending, with some ups and downs, to near sea
level, where the northern edge of the forest borders the
salt marsh. You will discover that the trees do not fill a
deep hollow at all, and that the tallest of them does
not exceed 8 or 10 meters in height.
Now let's return to the crest of the secondary dune. If
the wind, which is almost always present, is coming
from the ocean, notice that it is strongest at this point.
It is somewhat more gentle as you move down to the
beach; and going in the other direction — into the
forest — it diminishes almost entirely.
If this is a particularly windy day you may be able to
feel some of the salt spray that the wind has picked up
from the crests of the waves. This salt-laden wind is the
clue to the trimmed-hedge appearance of the forest. It
Osmosis: G, I
Devise an experiment to demon-
strate the process by which salt
removes the water from leaves. (A
science teacher can help.) This in-
teraction is the reason the maritime
forest trees do not grow to their
"normal" height and the reason that
plants intolerant of salt spray can-
not grow at all in the dune-and-
does not really have a shearing action, like a hedge-
clipper, though the effect is the same.
All the plants in the dune-and swale community are of
necessity tolerant of salt, for they are directly exposed
to the salty ocean breezes. And what happens when the
wind sweeps over the secondary dune? Salt is deposited
on the highest branches and leaves of the forest trees.
These are much less tolerant of salt than the dune-and-
swale plants, and the new buds and leaves at the top
are killed. So the forest cannot grow higher than the
secondary dune, and once they have reached the crit-
ical level the trees can grow sideways only. The spread-
ing branches at the top thus form a dense canopy that
from the dune crest looks almost solid enough to walk
on. The vegetation below this dense cover is affected
little by the salt-laden wind; but as you can see it is de-
prived of most of the sunlight that falls on the forest. So
only plants that are tolerant of shade can survive in the
understory and on the forest floor. You will not find any
beach grass here, though a few of the sun-loving pines
grow in the edges of the forest on the secondary dune
and near the marsh.
Most of the trees
of the maritime
forest can be iden-
tified from the
shapes of their
leaves. Shown are
(2) sassafras, and
In Fire Island's largest stand of maritime forest, three
species of trees are clearly dominant. An examination
of the canopy will show that it is made up mostly of
American holly, sassafras, and juneberry. Where condi-
tions vary, you'll find other species. In boggy places
there are sour-gums (swamp tupelo) and swamp azalea
(a tall shrub rather than a tree). There are scattered
black cherries, and here and there a big oak (big for
the maritime forest, that is). Only where an opening in
the canopy admits enough sunlight can you find a
It won't take you long to learn all the tree species in this
forest. And since the vegetation of the forest floor is not
greatly diverse, you should be able to identify the com-
mon shrubs and herbaceous plants with a little work.
Why do you think so few species grow here? It is not
entirely a matter of available sunlight; consider also
such factors as the sandy soil and the salt that rain-
storms wash from the uppermost foliage onto the forest
Detailed studies of the plantlife in the maritime forest
at Sailors Haven have enabled scientists to trace the
history of this unique community quite accurately. Care-
ful observation will enable you to discover some of the
Profiling a Community: I, G
Stake out a 10-meter-square plot of
maritime forest (get permission from
the ranger) or a narrow strip of the
forest or thicket bordering the
boardwalk, and make a profile
diagram of the habitat. Be sure to
include any birds, insects, and
other animals you observe. The
generalized maritime forest dia-
gram on p. 60 can serve as a guide.
To get a greater variety of plant
species, you might pick a plot that
includes a boggy spot or a forest
clues yourself. Notice, for example, that the dominant
forest trees — holly, sassafras, juneberry — are vigor-
ous and healthy. There are very few dead specimens of
these trees. On the other hand, there are a number of
dead oaks, redcedars, and pitch pines — some standing
and some on the ground — but very few living speci-
mens. This suggests that the forest has undergone a
fairly recent change; that the pines, oaks, and red-
cedars are on the way out; and that the holly, juneberry,
and sassafras are here to stay.
If climatic changes, severe storms, or other events do
not occur to upset the present balance, the forest may
remain for the foreseeable future in its present state.
We call such a stabilized forest a "climax community."
Climax communities come about through a process of
natural succession, which may require a hundred or a
thousand years to run its course. In the case of the
maritime forest here, it appears to have required about
250 years. But barrier islands, creations of the winds
and currents, are subject to sudden drastic alteration,
or even destruction, by these same forces. So the con-
cept of a climax community doesn't mean quite the
same here as it would in a mountain forest — where
even a fire or an unusually violent storm generally does
no more than cause a setback to an earlier stage in
succession. One winter storm could cut Fire Island in
half at this point, eliminating the forest. Also, the migra-
tion of the barrier island toward the mainland might re-
move the habitat. At Assateague Island National Sea-
shore in Maryland and Virginia, cedar stumps on the
beach mark the location of a former swamp.
Sometime between 200 and 300 years ago the site of
this forest was an area of bare, windblown sand. But it
was not to remain barren for long. It was soon invaded
by the seeds of pioneering dune plants. First, while
sand was still being deposited on the dunes, came
beach grass. This is the same plant now dominant on
the windward side of the primary dune. In spots where
the wind was removing sand, it was probably woolly
beachheather and seaside goldenrod that first gained a
foothold. Woolly beachheather not only pioneered, but
helped stabilize the habitat by trapping blowing sand.
But how did these pioneering plants get the nourish-
ment all living things need for growth and reproduc-
tion? There are virtually no nutrients to be derived from
sea sands; so they had to get their food from the air —
minerals borne on the winds both from sea and from
land. As the plant communities developed, they added
Comparing Communities: A, I, 7
Make a comparative study of the
maritime forest and a high thicket
community. Chart the species of
woody plants and their heights,
height of protective dune, distance
from ocean, and species of herb-
aceous plants and birds and other
animals. If you have a camera you
can take pictures to show differ-
ences and similarities. If you can
draw even a little bit, make profile
diagrams of the two habitats. It is
best for comparative purposes if
you choose two locations at ap-
proximately the same distance from
the ocean. This will eliminate dis-
tance from the ocean as a cause of
differences you discover between
the two forests. Because of the
prevalence of poison-ivy in the
thicket, you should make most of
your observations at the edge, or
along established trails and board-
organic material to the sand, and gradually an environ-
ment was created that enabled increasingly diverse
plant associations to grow.
As the pioneer plants spread over the dunes, they cre-
ated conditions favorable to such plants as bearberry,
bayberry, poison-ivy, Virginia creeper, and beach-plum.
In the more stable places, pitch pine and redcedar were
able to get a foothold. These woody plants — shrubs,
vines, and small trees — then created an environment
that permitted the development of still another plant
community, which was dominated by blackcherry, post
oak and other oaks, and highbush blueberry, and by
pitch pines and redcedars persisting from the previous
community. The other early plants, from beachgrass to
beach-plum, had by this time either disappeared or de-
clined, because conditions were no longer favorable for
them or because they could not successfully compete
with the new plants for the available food, moisture,
living space, and sunlight.
community has by now been almost entirely replaced
by the holly-sassafras-juneberry maritime forest. We
can't pinpoint the time when this transition began, but
some of the trees have been examined to determine
their ages. A core taken from one American Holly shows
that it began to grow about 1804, the year Lewis and
Clark started their western expedition. The apparent
stability of this forest suggests that it will remain for a
long time to come, barring natural catastrophes or
The process of natural succession occurs because
a plant community creates conditions that favor other
species at its own expense; thus each community is
replaced by another until a climax community — one that
does not in this manner seal its own doom — is estab-
lished. The fascinating thing about succession at Fire
Island is that you can retrace it, in a sense, by walking
from the beach to the maritime forest; you move from
bare sand through a beachgrass-dominated zone to the
shrubs of the swale to the forest hiding behind the pro-
tective secondary dune. You can find all the plants
mentioned above, if not in clearly demarked communi-
ties at least roughly in the same order of occurrence as
the order in which they became established in the suc-
It is not only plants that follow a successional pattern.
As you pass through the various zones from beach to
7.5m height of secondary dune
The Maritime Forest
Maritime forests typically develop
through the process of natural succes-
sion in areas first supporting such soft-
stemmed plants as beachgrass or sea-
oats, and usually have canopies de-
formed by wind and salt spray. Like
other plant communities, they have
characteristic associations of animals.
About 11 species of mammals and twice
as many birds breed in the Fire Island
forest; many others forage in it or pass
through on migration. In earlier times
it probably sheltered otter, gray fox,
bobcat, and black bear, as well as the
red fox and deer we see today.
forest, make a note of what animals you see, and what
plants they are feeding on or using for perches, shade,
or other purposes. If you make such observations over
a long enough period of time, you should be able to de-
velop a distribution pattern that will roughly parallel the
changes that took place in the animal populations dur-
ing the succession from bare sand to maritime forest.
You will learn more about the concept of natural suc-
cession in plant-and-animal communities in the chapter
on salt marshes.
An ecosystem is a plant-and-animal community and its
physical environment. For example, when we speak of the
salt marsh ecosystem we mean, along with the living
sedges, grasses, algae, and other plants, the mud or sand
in which they are rooted, the invertebrate and vertebrate
animal life, the dead plant and animal material, and the
water, minerals, atmosphere, and incoming solar energy.
The salt marsh can be considered part of a larger eco-
system, the estuary; on the other hand, two well defined
zones of the salt marsh ecosystem with distinctly different
plant associations can be treated as separate ecosystems.
When you encounter any new word beginning with "eco-",
keep in mind that it is taken from the Greek word eko,
meaning "home." Ecology is the science of the home
(-logy = science) — that is, the study of the relationships
between the living things in an environment.
Wet Your Feet in the
At low tide, walk out onto one of the expanses of flat
terrain on the island's north shore between low- and
high-tide marks. If you're in a zone that is covered and
uncovered by each day's tides, you're probably in the
salt-marsh cordgrass community. In thousands of hec-
tares of our coastal wetlands, cordgrass is the only
rooted plant growing. It thrives best in soil that is in-
undated about half the time. Along tidal creeks, it may
be as tall as a man.
This is probably the most rewarding of Fire Island's life
communities for the wildlife watcher. And don't make
the mistake of thinking that the animal life consists of
the ducks, shore birds, and wading birds that fly off at
your approach. Look down as well as up — and look
carefully. If you're not making too much disturbance,
you may spot the fiddler, an important citizen of the wet
marsh. It's only a crab — and a small one at that. But this
crab looks as though its growth hormones have gone
awry; it is waving an oversize foreclaw back and forth
like a huge fiddle. As you approach, the crab will scurry
toward one of the holes in the mud, apparently unhin-
dered by the burden of the claw it carries before it. The
fiddler may reach the entrance to a burrow, quite likely
not its own, before you can catch it. But with patience
you should get a specimen to examine. It won't harm
The fiddler crab,
Uca pugnax, with
long shell, is Fire
crab. The related
Uca musica — a
noisy creature —
has a shell only
8 mm long!
you. Look at its other foreclaw — the normal-sized one.
It is spoonlike and is used, logically enough, in feeding
upon minute plants scraped from the mud. This comical
little show-off is the male of the species; the female fid-
dler has two spoon-claws, which suggests that she can
feed more efficiently than the male. Perhaps this is a
necessary difference, for she must produce the eggs
that maintain the species. The male's big claw, used in
mating and territorial displays, is useless for feeding.
The fiddler crab and saltmarsh cordgrass are well
adapted to a half-land, half-water existence. The crab
can breathe quite well out of the water, so long as its
gills remain moist. The cordgrass is one of the few
flowering plants that will grow in the lower intertidal
zone; another species, saltmeadow cordgrass, grows
on the drier flats where only the highest tides reach.
Low cordgrass marsh is the more productive; one
hectare can produce 10 tons per year of green plant
material, dry weight — more, in fact, than any other na-
tural land community. This is a bountiful base not only
for this zone but for the adjacent estuary that is en-
riched by it. The saltmarsh cordgrass community is an
ideal place to study Earth's natural rhythms and life
What Good Is a Salt Marsh?
This question reflects our historic indifference to and
abuse of a priceless natural resource. Much of our exten-
sive coastal marshland has been drained for farming or
mosquito control; filled in for housing, industry, highways,
and recreation; used as a handy place to dump refuse;
and badly polluted by sewage and factory effluents. Yet
the salt marsh is the most productive of all natural com-
munities, exceeded only by fertilized sugar cane fields.
The abundant growth of green marsh plants provides the
base of a food pyramid unsurpassed in variety and rich-
ness. The animals that feed on the marsh plants are in turn
eaten by predatory animals. Besides the profusion of
vertebrate and invertebrate animals that spend all or most
of their life cycles in the tidal marsh, there are many
marine species that use them as nurseries.
Though you may not have realized it when eating seafood
such as fish sticks and crab cakes, many of the animals
that are important food for man are caught in the marsh.
Many hatch and spend their early lives there, or live in
estuarine or offshore waters on nutrients that flow from
the rich marsh ecosystem. Marshes offer protective cover
and abundant food for fishes, molluscs, and crustaceans.
The marsh is also a valuable habitat for nonaquatic forms.
Most of these are rodents, such as the meadow vole, that
feed upon the vegetation, or predators that feed both on
rodents and upon fish and other aquatic life. Eagles,
ospreys, marsh hawks, owls, ducks and geese, shore
birds, gulls and terns, rails, herons of many kinds, dia-
mondback terrapins and snapping turtles, raccoons, mink
. . .the list is almost endless. Not every one of them is
found in the Fire Island marshland; but if you're a bird
watcher or nature photographer you'll do well to spend
some of your time in this habitat.
The existence of much of our coastal lowland derives from
salt marshes. The vegetation slows the movement of water
and traps sediments, building up the land. It also helps
prevent shoreline erosion by breaking the force of waves,
currents, and wakes of vessels.
The value of salt marshes for recreation is recognized by
many, especially waterfowl hunters and wildlife watchers.
As for educational and scientific benefits, marshes are
excellent laboratories for ecological studies, and a knowl-
edge of salt-marsh ecology is absolutely essential in
marine fisheries research.
night heron has
a thicker neck,
heavier body, and
shorter legs than
most of the heron-
and its habits are
nal. Look for it
early and late in
Coastal marshland is called "wasteland"
by many who, ignoring its value, wish to
convert it to "useful" purposes. Yet a
cordgrass marsh produces four times as
much plant growth as a cornfield — with-
out artificial fertilizer or cultivation!
As cordgrass plants break up or die, fragments of de-
caying plant material, called detritus, are washed by the
receding tides into the bay, where they furnish food for
amphipods, ostracods, isopods, polychaete worms, and
other animals. These detritus feeders are eaten by small
predators such as pipefish and sticklebacks; the small
predators in turn are fed upon by flounders and other
fish that provide food for man and larger predators.
The marsh itself is rich in variety and abundance of
animal life. Many burrowing animals feed on green
plants — cordgrass and algae — or on fine particles of
organic matter contained in the mud. These and all the
other animals of the broad marsh-bay ecosystem are
dependent upon a group of organisms we call decom-
posers: the fungi and bacteria that begin the process of
breaking down the cordgrass and other green plants,
and the small crustaceans, worms of various types, and
other invertebrates that feed on the detritus and convert
it to animal protein that feeds the host of predators.
Even direct feeders on green plants, such as the purple
marsh and fiddler crabs, can be considered decom-
posers, since their digestive processes only partially
utilize the plant material, and their fecal pellets contain
fine particles that become part of the detritus.
The salt marsh is an excellent field for the study of the
process by which one natural community replaces another
and then creates conditions that bring about its own re-
placement by a third community. It would require more
than your own lifetime to follow the series of stages in the
succession process that leads from an abandoned farm
field to a mature broadleaf forest. But on Fire Island you
can observe the creation of new land from the sea and can
see the pattern of the successive stages that lead eventu-
ally to thicket, maritime forest, or other relatively stable
community. On the bay side of the barrier island, the first
stage in the succession story is the creation of a new
Look for a place in an inlet or tidal creek where mud has
built up above the low-tide mark and enabled a clump or
two of salt-marsh cordgrass to take root. The underground
stems of this plant spread rapidly, sending up new tufts of
grass that trap more sediment and form an island, or build
out from the existing marsh. As the tides deposit more silt
and the dead grass stems and leaves accumulate along
with windblown sand and shells and other remains of dead
animals, the marsh becomes higher — and the tides cover
it for fewer hours of the day. Eventually, after many years,
a level beyond all but the highest tides is reached; by this
time the saltmarsh cordgrass has been replaced by salt-
meadow cordgrass, and we have a high-water marsh. The
low-water marsh, by its own success, has eliminated the
conditions that favored it and has thus paved the way for
its replacement by a plant community adapted to the
Salicornia, or glasswort, which has become established in
the later stages of the low-water cordgrass marsh, remains
in the new marsh community, where along with black
grass, three-square rush, and spike rush it mixes with the
salt-meadow cordgrass. As the marsh builds up still
higher, the cordgrass disappears, leaving a stand of the
other three plants. These eventually give way to a border-
line community between marsh and upland, such as
Phragmites (reed) grassland. When the soil base has
built up to the point where it is no longer affected by even
the highest tides, it supports an upland community. This
might be beachgrass grassland, low thicket, or any one of
several other types, depending upon such factors as
deposits of windblown sand and proximity of the water
table to the soil surface.
By walking from the bay across the marshland to the up-
land, you can see the same succession of communities
that has occurred in one locality over a long period of
time. The pattern may not exactly parallel what has been
described above; it will vary, depending upon what part of
the barrier island you are exploring.
On the mainland, natural succession generally proceeds
until a community develops that does not create condi-
tions leading to its replacement by another. This is called
a climax community; it will prevail until fire, flood, other
natural catastrophe, or the activities of man either elimi-
nate the plant community or alter it so drastically as to set
it back to an earlier stage of succession. On Fire Island,
however, the dynamics of barrier-beach ecology are such
that a climax community in the usual sense does not exist.
The is/and itself is migrating toward the mainland as the
ocean eats away at its south shore and new marshland
builds up on the bay side. Perhaps the nearest thing to a
climax community on the island is the holly-juneberry-
sassafras Sunken Forest, which has developed from bare
sand over a period of two centuries.
For a fuller understanding of natural succession, refer to
some of the books in the Reading List.
Food Web of the Salt Marsh
Backyard Ecology: I, G, 7", Y
The process of natural succession
is so slow that the changes leading
to a climax community may span
several human lifetimes. But you
can observe the early stages by
watching a newly abandoned farm
field, an empty lot, or a corner of
your backyard or schoolyard
allowed to return to nature. Record
the changes in plant and animal life
as one community creates condi-
tions that enable another to replace
it. During the first year the grass is
not mowed, a piece of lawn will be
converted to a patch of wildflowers.
The increase in numbers and kinds
of animals will be noticeable as the
"weeds" grow high and shrubs and
tree seedlings gain a foothold. Keep
a photographic record of the suc-
cession process for as many years
as you can.
The diagram of the saltmarsh food web shows how in-
tricately all these animals are interrelated and how all
are totally dependent upon the green plants and ulti-
mately on the sun's energy. Because the saltmarsh
provides much of the nutrient for the adjacent estuary,
the diagram includes part of the Great South Bay
Where there is no regular (daily) inundation by the tides,
a different type of saltmarsh will develop. On Fire Island
you will find several kinds of high, or dry, marsh. There
are solid stands of Phragmites, the towering reed grass.
This plant is utilized by so few organisms that it is al-
most valueless as wildlife habitat. There are also ex-
panses of saltmeadow cordgrass, in the zone flooded
only by occasional tides. Saltmeadow cordgrass is not
so productive as saltmarsh cordgrass. Here the fiddler
crab is largely replaced by the purple marsh crab,
though the zones of the two overlap and the latter, pri-
marily a vegetarian, sometimes preys upon the smaller
fiddler. Among shore birds, the greater yellowlegs is
often seen fishing for minnows in the marsh waterways,
while the lesser yellowlegs prefers the short-grass
marshes where it hunts its food, mainly insects and
small crustaceans, in wet places and shallow pools.
The Peregrine, an Endangered Species
Some of the birds and mammals once
common on our barrier islands and in
our offshore waters have been brought
close to extinction by man's greed and
carelessness. Destruction of habitats,
environmental pollution, and ruthless
hunting have all contributed to the de-
cline of such species as the noble pere-
grine falcon, which is perilously close
to disappearing but can still occasion-
ally be seen hunting rodents in the salt
marshes and other coastal habitats. In
the middle decades of this century the
peregrine suffered enormous losses
from such pesticides as DDT. Stricter
environmental controls and better pro-
tection may bring the population back
to a level that will assure its survival.
Knowledge of any animal's habits and familiarity with
its preferred haunts will make wildlife finding more re-
warding foryou. Keeping records of your observations —
times, habitats, behavior, etc. — will enhance your ex-
perience and build your skills.
The wild animals of Fire Island do not always conform
to the standard behavior of their species as described
in the field books. For example, the muskrat, whose
lodges dot coastal and inland marshes on the mainland,
doesn't even seem to build a mound of vegetation
as a home here. Instead, it digs burrows in the walls of
mosquito-drainage ditches or in the sandy banks of
small ponds. It will take some searching to get so much
as a sight of this rodent. The muskrat ordinarily is
preyed upon by many birds and mammals. But here it
is probably not an important link in the saltmarsh food
chain. Snapping turtles are not abundant. Still, the
muskrat must be on guard against other regular ene-
mies, such as red foxes and large hawks. If you're
going muskrat-watching, be sure you know how to rec-
ognize this rodent's tracks. Watch for them in muddy
spots along the ditches and the edges of small ponds
and cattail marshes. The records of wild mammals on
Fire Island are quite sketchy. You can help fill the
gaps — so report your observations to the park rangers.
ftiMiiMir«m ' j^l' -JiSBjfer'
Who's Who in the Zostera
You don't need a boat to get on close terms with the
life community of Great South Bay. This shallow coastal
lagoon, as much as 8 kilometers wide and many times
as long, slopes so gradually from the shore that you can
wade out hundreds of meters from the narrow beach.
Simple collecting gear, most of which you can salvage
or make yourself, will enable you to sample the fasci-
nating array of living things. At the base of this com-
munity is a plant called eelgrass.
A freshwater plant, not at all related to Zostera, also
goes by the name "eelgrass." To confuse the matter
further, neither of these plants is a member of the grass
family. The name that definitely distinguishes Fire Is-
land's eelgrass from other plants is Zostera marina
(pronounced zoss-TARE-uh ma-REE-na).
You'll find Zostera growing thickly in much of the shal-
low offshore water on the lagoon side of Fire Island. It
grows in mud or soft sand bottoms, generally in brack-
ish waters but also sometimes in highly saline areas. It
is one of only a few flowering plants that have gone
back to the sea from the land, where that branch of the
plant kingdom evolved. Almost all of the green plants
in the sea are nonflowering, and are loosely grouped
under the term "algae."
The Zostera Community
Hermit-crabs, the clowns of the eelgrass
jungle, walk about with their snailshell
homes on their backs, scavenging for
bits of animal matter on the bottom.
Shown on the facing page are a few of
the animals and plants that live not on
the floor of the eelgrass community but
on the Zostera plants themselves.
Examine Zostera closely. You'll see that it does indeed
resemble grass, even to having jointed stems. With a
hand lens you'll be able to see its tiny green flowers,
which develop in grooves on a leaflike spike. Unlike
algae, it has true leaves, which are ribbonlike and flex-
ible and grow to a meter in length. The beds of Zostera
are extensive, and most of the beach wrack on the
shore of Great South Bay consists of dead leaves of this
Why is this plain-looking saltwater weed so important?
Certainly, few of the animals in this community eat
it, though it is the staple diet of the American brant,
a small goose that you may see in winter along this
coast; and several ducks are known to eat small quan-
tities of it. But look at the plant through your hand lens.
Feel its texture. That slippery coating is a growth of
algae — and it is on this that a great variety of organisms
feed. Snails, including the centimeter-long Lacuna and
the iridescent Margarita, are the most abundant of
these algae feeders.
Mitrella lunata Caprella
Also found in enormous numbers on and amongst the
Zostera plants is Nassa, a predaceous snail that feeds
on other molluscs. Nassa itself is devoured by the
hermit-crab, which adds insult to injury by taking its
victim's shell as its home. Examine Zostera leaves for
small, gelatinous masses of bright yellow eggs of Nassa.
Your search may reveal another animal that you first
take to be a snail but is actually a worm, Spirorbis. Its
home is a minute, limy tube coiled in such a way as to
resemble the shell of a snail, and cemented to one spot
on the Zostera blade. It has even developed its own
version of the operculum, the horny plate that serves to
close the entrance to a snail's shell: in Spirorbis, one
gill is modified to form an operculum that closes the
end of its tube!
Besides these and other tube worms and snails, inhab-
itants of the Zostera beds include clams, small fishes,
edible crabs, horseshoe-crabs, and smaller crusta-
ceans. With a few sweeps of a fine-mesh net you should
be able to capture many of these organisms. With luck
you'll get a sea horse or its close relative the pipefish.
a Elysia d snail (Lacuna vincia)
b bryozoan, algae e snail eggs
c Spirorbis f Didemmum
The Eelgrass Microhabitat: I
Examine some eelgrass plants
(Zostera) with a hand lens and, if it is
available, a low-power microscope.
See how many kinds of organisms
you can find and identify, using
books listed in the Appendix. Don't
overlook the roots. Do any of the
organisms appear to be feeding on
Zostera itself? Put your sample into
a jar or larger container of bay
water, and examine it at intervals to
see if eggs hatch or other changes
occur. Keep it out of the sun, to
prevent warming and loss of oxy-
gen. Replenish frequently with fresh
sea water. These water changes
may introduce new organisms into
Put your living specimens into a container of bay water;
a white basin is good because it makes seeing the
smaller forms easier. Be sure to return all living animals
to the bay; you won't be able to keep them alive out of
their natural environment unless you have a well de-
signed marine aquarium set up .
Though they are part of the larger Great South Bay eco-
system, the Zostera beds are in themselves a dynamic
plant-and-animal community. You could easily spend a
whole summer getting acquainted with the inhabitants
of this shallow offshore zone.
Let's see how a few of these animals fit into the Zostera
community. We might start with one of the worms. The
word "worm" is a bit of a problem, though, because
many unrelated forms of animal life are called worms.
Nereis virens, the clam worm, belongs to the phylum
Annelida, which, with more than 6,000 species, is the
best known of the "worm" phyla. It includes earth-
worms, leeches, and the Tubifex worms you buy at the
pet shop to feed your tropical fishes.
Nereis virens (left)
and detail draw-
ings showing the
head of Nereis
with its pharynx
retracted and ex-
Nereis belongs to the class of segmented worms some-
times called "paddle-footed annelids." During the day
it burrows in the mud and sand; at night it emerges and
swims about like an eel. It is a voracious predator, feed-
ing on invertebrates, including other worms, and em-
ploying an unusual device for capturing and eating its
prey. Its two horny, notched jaws are well back inside
its body. Suppose it comes upon a small crustacean
such as the skeleton shrimp, only two centimeters long.
The clam worm turns its pharynx inside out, everting
it right through its mouth and bringing the jaws into
position for action. Seizing the crustacean in its jaws,
the worm pulls its pharynx back inside its body, where
the jaws tear the shrimp to pieces.
Predator though it is, the clam worm is not at the top
of the food chain. When swimming about at night it
often falls prey to fishes. In fact, large numbers of clam
worms are dug from tidal flats to be sold to fishermen
for use as bait.
The Web of Life: G, /, A, T
Individually or as a team, capture or
observe and identify as many ani-
mals of the Zostera community as
you can. Draw a food web showing
how each fits into the community —
as predator, scavenger, browser, or
filter feeder — and be sure to in-
clude plankton and algae, as well
as any birds you see feeding in the
zone. You will need to use refer-
ence works to determine the food
habits of the animals. The food web
can be constructed at home or
school from your field notes.
If you should capture a specimen of Nereis virens, use
a bit of caution. You're in no danger from this 30- or
40-centimeter-long worm; but those jaws can give you
a painful nip. Unless you can seize it behind the head
as experienced fishermen do, use a net to scoop it up.
With your captive in a container of water, notice how it
swims, snakelike, with the help of the paddle-like ap-
pendages on each body segment. Notice its metallic
iridescence and its sense organs — eyes, palps, ten-
tacles, and cirri.
Since the molluscs of the Zostera community include
filter feeders, browsers on algae, and predators, we
can't place them as a group in any level of the food
chain. The hardshell clam is one of the most interesting
to us, since it is a favorite food of man. If you can bor-
row a clam rake, it shouldn't take you long to get a spe-
cimen or two. You might even be able to excavate one
with your toes as you wade in the shallows; for although
the hardshell is a burrower, it usually remains just be-
low the surface of the sand. It feeds by extending its
siphon, or "neck" — which is actually a part of the pos-
terior end of the clam's mantle. Through the siphon it
draws water, using its gills as internal filtering devices
V ; ^"
.v. - /
The oyster drill, which rarely reaches
2.5 centimeters in length, bores neat
round holes in the shells of its victims
and sucks out the soft parts of their
bodies. You will find shells on the beach
that show that their owners perished in
this way. Such shells with holes ready-
drilled can be easily strung into neck-
to extract any microscopic organisms (plankton) taken
in with the water. Then the water, along with waste
products, is discharged through the same opening.
Many molluscs, including oysters, mussels, and scal-
lops, and many other invertebrate animals of the bay
are filter feeders-reflecting the importance of small
plankton in the food web.
The hardshell clam, like most organisms in the Zostera
community, is itself food for other animals. Small clams
are eaten by the abundant horseshoe-crabs, which bur-
row under the surface of the sand in search of prey.
The oyster drill, a carnivorous snail, is able to cut a
hole through the shell of a clam and devour it. And the
clam worm, true to its name, is a predator on the hard-
All crustaceans breathe with gills and
have two pairs of antennae. True crabs
are crustaceans with a reduced abdo-
men that is folded under the body and
cannot be seen from above. The hermit-
crab's abdomen is long — and it is invis-
ible only because it is coiled into a snail
shell. Also included in the Crustacea
are barnacles, amphipods, isopods,
copepods, shrimp, lobsters, crayfish,
sowbugs, and water fleas.
Crustaceans are well represented in the Zostera com-
munity. The members of this class are so varied in form
and life style that we can't choose one that is typical.
Perhaps we can have the most fun with Pagurus long-
icarpus, the small hermit-crab. (The last word is hy-
phenated because these curious animals are not true
crabs.) Their posterior parts lack the hard, crusty exo-
skeleton (outside skeleton) of most larger crustaceans;
they protect themselves by inserting their soft ab-
domens into a hollow object, generally the shell of a
snail. This protection is not complete; predatory fish
swallow them shell and all.
You can spend fascinating hours observing these en-
gaging creatures as they scurry over the bottom, drag-
ging their portable homes with them. You may see two
hermit-crabs fight over an empty shell, or watch one
trying to dispossess another — for as the hermit grows it
must seek larger quarters. Especially amusing are its
antics as it tries out a series of empty shells; but its
movements are so quick you won't be able to see just
how it's done. Naturally, it does not want to remain de-
fenseless for long. Notice when you pick up a hermit-
crab that it closes the shell opening with its larger pin-
cer. Different species utilize the shells of different snails;
in each case the anterior end of the occupant is modi-
fied to fit the particular house doorway. For example,
some West Coast hermits inhabit tooth-shells; their
right claws are cylindrical in form, snugly fitting the cir-
cular openings of the shells. Even when they are
stranded on land between tides, they are closed up so
tightly that they are in no danger of drying out.
With the aid of your hand lens, you'll be able to see
tiny eyes at the ends of Pagurus' eye-stalks. When the
hermit is closed up in his home, notice how its small
left claw neatly fills in the part of the shell opening not
closed by the large claw. If you chance to see a hermit-
crab out of its shell, examine the posterior end of its
abdomen; you'll see that the last pair of abdominal ap-
pendages have been modified into hooks, which serve
to fasten the crab in its shell. Place it next to an empty
snail shell in a container of cool bay water and watch it
back in — or better yet, give it a choice of two or three
empty shells and observe the selection process.
The skeleton shrimp, Caprella, is actual-
ly an amphipod. Although tiny (males
2 cm, females smaller), it is a voracious
predator. Besides devouring smaller
crustaceans, it feeds on algae and other
minute plants growing on Zostera. The
20-cm pipefish — as curious a creature
as the related seahorse, preys on
The Eelgrass Blight
What do you suppose would happen to Pagurus and the
many other animals in this habitat if Zostera should dis-
appear? In the early 1930s the abundant eelgrass beds on
the east coast were hit by a disease that almost wiped
them out. The effects were far-reaching. Flounder fishing
declined; clams became scarce; pipefish almost disap-
peared. The American brant, whose diet before 1932 had
been about 90 percent eelgrass, had much difficulty
adapting to other plant foods, and many of the birds
starved to death. But Zostera came back during the 1940s
and is now abundant enough to support and shelter a rich
Not so easy to find as Pagurus is the northern pipefish,
which dwells in the Zostera beds, much of the time
clinging to the plant's leaves and stems where it is well
camouflaged. It shares with its close relative the sea-
horse a curious habit: the eggs are deposited by the
female in a pouch in the male's underside, where they
remain until hatching. After hatching, the young pipe-
fish use the pouch as a retreat in time of danger.
The pipefish feeds extensively on the amphipod, Ca-
prella, which preys on the larvae of invertebrates that
feed on and in the Zostera beds, including some amphi-
pods that eat the decaying remains of Zostera itself.
The more you learn about the creatures in this habitat,
the more you realize that all are interrelated and all are
dependent on Zostera. But what about the fisherman
who is, understandably, annoyed when his boat propel-
ler is fouled by eelgrass? Is he aware that the summer
flounders he is angling for feed on the pipefish, and
thus are intricately linked with the plant and all the
other organisms in the community?
Can you construct a food chain beginning with Zostera
and ending with man? (You will find good references
in the reading list in the back of this booklet.) Tip:
flounders eat blue crabs.
Your own community functions through the efforts of many
persons doing many different jobs. In the same way, each
organism in a natural community has a role, or niche. All
green plants are producers, converting raw materials into
food that supports the animal component of the commu-
nity; but each plant species has a precise niche. For
example, beach grass functions in the dune-and-swale
community to capture moving sand and to stabilize the
dunes, making it possible for other plants to become
established. Pitch pines, beach plums, and other woody
plants not only provide food for insects, cottontails, and
whitetail deer, but also furnish shelter from sun and wind.
The cottontail's niche is that of herbivore; it converts plant
food into flesh. The red fox's niche is not so simple; it is
predator, herbivore, and scavenger all in one.
Sometimes two animals seem to be performing the same
function. But investigation shows that their niches are not
identical. The long-eared owl and the short-eared owl,
Asio wilsonianus and Asio flammeus, are a good illustra-
tion. These closely related birds have almost identical
diets, the bulk of their food being small rodents. But their
habits separate their functions in the island's ecology.
The long-eared owl prefers dense woodland and thicket
growth, and the short-eared owl prefers more open areas
such as sand dunes and marshes. Even where their hunt-
ing ranges overlap they play a different ecological role,
for the short-eared owl is most active by day and the long-
eared owl by night. Thus the former feeds on diurnal
species, the latter on nocturnal. How do the niches of the
greater yellowlegs and the lesser yellowlegs differ in the
Fire Island environment? Compare the roles of the white-
footed mouse and the meadow vole ("field mouse").
Adaptation: An inherited structural, functional, or behavioral characteristic
that improves an organism's chances for survival in a particular habitat.
Algae (pronounced "AL-jee"): A group of plants (singular, alga, pro-
nounced "AL-ga"), one-celled or many-celled, having chlorophyll, without
roots, and living in damp places or in water.
Brackish Water: Mixed fresh and salt water, as in estuaries and lagoons
where water from streams mixes with tidal waters.
Carnivore: An animal that feeds upon the bodies of other animals. (Para-
sites are not included in this definition.) Animals that feed chiefly upon
insects are more often referred to as insectivores.
Commensalism: The relationship between a host plant or animal and its
"guest," a species that shares the host's food without harming it. The flat-
worm, Bdelloura, is commensal, not parasitic, on the horseshoe-crab.
Deposition: The laying down of rock particles, by wind or in water.
Dune: A hill or ridge of wind-deposited sand. The windward side slopes
gently, while the lee side is steep.
Environment: All the external conditions — such as soil, water, air, and
organisms — surrounding a living thing.
Erosion: Any process by which materials of the earth's crust are worn
away or removed from the surface. Water, wind, and gravity are the usual
Estuary: The portion of a river or coastal wetland affected by the rise and
fall of the tide, containing a graded mixture of fresh and salt water.
Habitat: The place where an organism lives; the immediate surroundings,
living and unliving, of an organism.
Herbivore: An animal that feeds upon plants.
Invertebrate: An animal that lacks a vertebral column and internal bones.
Marsh: A wetland, salt or fresh, where few if any trees and shrubs grow,
characterized by grasses and sedges; in fresh-water marshes, cattails are
Phylum (plural phyla): The largest divisions in classification of either the
plant or the animal kingdom. Man belongs to the Phylum Chordata. Zostera
belongs to the Phylum Embryophta of the plant kingdom.
Plankton: The small plants and animals of fresh and salt waters that, lack-
ing swimming ability, drift more or less at the mercy of currents and form
the base of the food web in most aquatic ecosystems.
Predator: An animal that lives by capturing other animals for food.
Scavenger: An animal that feeds upon dead animals.
Swamp: A wetland characterized by mosses, shrubs, and trees. Usually
not covered by water the year around.
Amos, William H., The Life of the Seashore. McGraw-Hill, 1966.
Bascom, Willard, Waves and Beaches. Doubleday, 1964.
Berrill, N. J., The Life of the Ocean. McGraw-Hill, 1966.
Carson, Rachel, The Edge of the Sea. Houghton Mifflin, 1955.
Coe, Wesley Roswell, Starfishes, Serpent Stars, Sea Urchins, and Sea
Cucumbers of the Northeast. Dover, 1972.
Hay, John, and Peter Farb, The Atlantic Shore. Harper & Row, 1966.
Milne, Louis J., and Marjorie Milne, The Balance of Nature. Alfred A. Knopf,
Miner, Roy Waldo, Field Book of Seashore Life. Putnam, 1950.
Niering, William A., The Life of the Marsh. McGraw-Hill, 1966.
Ogburn, Charlton, The Winter Beach. Simon & Schuster, 1970.
Perry, Bill, Our Threatened Wildlife. Coward-McCann, 1969.
Petry, L, and L. Norman, Beachcomber's Botany. Chatham, 1975.
Shepherd, Elizabeth, Tracks Between the Tides. Lothrop, Lee, & Shepherd,
Sterling, Dorothy, The Outer Lands. Natural History Press, 1967.
Voss, Gilbert L., Oceanography. Golden Press, 1972.
Q2 Zim > Herbert S., and Hurst H. Shoemaker, Fishes. Golden Press, 1955.
Zim, Herbert S., and Lester Ingle, Seashores. Golden Press, 1955.
As we go to press with this book, the United States is
in the early stages of conversion to the metric system
of measurement. Though we urge you to think metric —
for most of the world does — we provide this table to
help you understand the measurements given in the
1.8 and add 32
^GPO:1 978-261 -215/8
For sale by the Superintendent of Documents, U.S. Government Printing
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As the Nation's principal conservation agency, the Department
of the Interior has responsibility for most of our nationally
owned public lands and natural resources. This includes
fostering the wisest use of our land and water resources,
protecting our fish and wildlife, preserving the environmental
and cultural values of our national parks and historical places,
and providing for the enjoyment of life through outdoor
recreation. The Department assesses our energy and mineral
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the best interests of all our people. The Department also has
a major responsibility for American Indian reservation com-
munities and for people who live in Island Territories under